ESM 266: Thermal infrared remote sensing

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ESM 266 Thermal infrared remote sensing
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(Wikipedia Infrared)
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Infrared remote sensing, to measure

• Surface temperature, through the atmosphere
• Atmospheric sounding
• Temperature and humidity
• Trace gas concentrations
• Radiation balance
• Emissivity

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AVHRR (NOAAs operational meteorological sensor)

• Antenna on roof of Ellison Hall
• http//www.icess.ucsb.edu/ and follow link to
  DATA-gtAVHRR Images

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Fusion between data on ocean temperature and
surface height
HRPT Data Handling
HRPT Gridding
calibrate, de-cloud, aggregate
TeraScan
extrapolate
HRPT downlink
SST grid
SST super data
AVHRR image
GOAL Local and advective components of upper
ocean heat balance
ocean height grid
TOPEX Gridding
TOPEX Data Handling
ocean height super data
TOPEX points
calibrate, aggregate
MGDR cracker
extrapolate
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Radiation principles

• All bodies radiate
• Hotter bodies radiate more at all wavelengths
• Radiation from a hotter body peaks at a shorter
  wavelength than from a cooler body

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Governing equation
Plancks equation (spectral curves on next slide)
Stefan-Boltzmann equation
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Definition of IR regions
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Atmospheric transmission of infrared radiation
http//www.pentec.com/instrumentation.htm
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Infrared spectral regions
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Emissivityobjects are not blackbodies

• Kirchhofs Law emissivity absorptance
• Probability of emission of a photon at a given
  frequency and angle is same as probability of
  absorption at same frequency and angle
• Emissivity Reflectance Transmittance 1
• (all functions of wavelength and angle)

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Definition of brightness temperature TB
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Relationship between T and TB
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Split-window methodsatmospheric correction for
surface temperature measurement

• Water-vapor absorption in 10-12 ?m window is
  greater than in 3-5 ?m window
• Greater difference between TB (3.8 ?m) and TB (11
  ?m) implies more water vapor
• Enables estimate of atmospheric contribution (and
  thereby correction)
• Best developed for sea-surface temperatures
• Known emissivity
• Close coupling between atmospheric and surface
  temperatures
• Liquid water is opaque in thermal IR, hence
  instruments cannot see through clouds

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Sea-surface temperature, June 22, 2000
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NASAs Earth Observing Systemmissions with IR
capability

• TRMM
• CERES
• Landsat-7 (launched April 1999)
• ETM has 60 m band at 10.5-12.5 ?m
• EOS Terra (launched December 1999)
• CERES, MODIS, ASTER, MOPITT
• EOS Aqua (launched May 2002)
• AIRS, CERES, MODIS
• EOS Aura (launched July 2004)
• HIRDLS, TES

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CERESCloud-Earth Radiant Energy System
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ASTERAdvanced Spaceborne Thermal Emission and
Reflection Radiometer

• 14 bands (15-90 m) in VIS, NIR, SWIR, and TIR

Shortwave infrared
Thermal infrared
Mauna Loa images
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ASTER spectral bands on model atmosphere
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MODISModerate-Resolution Imaging
Spectroradiometer

• 36 bands, 1 in SWIR, 6 in mid IR, 10 in thermal
  IR
• Measurements of
• Surface/cloud temperature
• Atmospheric temperature
• Cirrus clouds and water vapor
• Ozone
• Cloud top altitude

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AIRSAdvanced Infrared Sounder

• 2400 bands in IR (3.7-15 ?m) and 4 bands in
  visible (0.4-1.0 ?m)
• Absorption signature around 4.2 ?m and 15 ?m
  (CO2) and 6.3 ?m (H2O) enables temperature and
  humidity sounding to 1 km vertical resolution
• Spatial resolution is 13.5 km
• Complemented by microwave sounders to deal with
  clouds

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HIRDLSHigh-Resolution Dynamic Limb Sounder

• Sound upper troposphere, stratosphere, and
  mesosphere for temperature and a variety of gases
• O3, H2O, CH4, N2O, NO2, HNO3, N2O5, CFC-11,
  CFC-12, ClONO2
• 21 bands from 6.12 ?m to 17.76 ?m

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TESTropospheric Emission Spectrometer

• High-resolution infrared-imaging Fourier
  transform spectrometer
• Spectral coverage of 3.2 to 15.4 µm at a spectral
  resolution of 0.025 cm1
• Line-width-limited discrimination of most
  radiatively active gases in the Earth's lower
  atmosphere

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Operational Missions

• GOES (Geostationary Operational Environmental
  Satellites)
• Imager and sounder
• POES (Polar-Orbiting Environmental Satellites,
  i.e. AVHRR)
• Two satellites provide coverage with maximum
  delay of 6 hours
• Latest is NOAA-15, launched May 13, 1998
• NPOESS (National Polar-Orbiting Environmental
  Satellite System)
• Joint NOAA/NASA/DoD mission
• Launch no earlier than 2011
• Imaging, microwave, and sounding instruments

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Land surface temperature from MODIS

• Go to the MODIS Land Global Browse page
• Select the MOD11/MYD11 checkbox (Surface
  Temperature)
• Enter date range
• Select satellite (Terra and/or Aqua)
• Select Collection (5 is most recent)

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Active fire detection

• MODIS Fire and Thermal Anomaly website

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Ocean surface temperature from MODIS

• MODIS ocean web site
• Click on Quality Assurance to get the browse tool
  intuitive?

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How does all this work?

• As noted in previous lecture, a great feature of
  NASAs EOS program is that the algorithms are
  peer-reviewed and published in algorithm
  theoretical basis documents
• Each instrument has a page with links to these
  ATBDs, e.g. for MODIS, one can go to Zhengming
  Wans ATBD for land surface temperature
• The algorithm uses MODIS bands 31 (10.78-11.28µm)
  and 32 (11.77-12.27µm)

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Dr. Wans equation is
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Spectral emissivity library
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Fire detection

• Planck equation is a steeper function of T at
  shorter wavelengths

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Consider a pixel with a small fire
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Can solve for f, Tf, if Tb is known